FDG PET/CT in IgG4-related Disease Involving the Urethra.

Urethral involvement in IgG4-related disease is rare. We describe FDG PET/CT and delayed pelvic PET/MRI findings in a woman with IgG4-related disease presenting as urethral wall thickening with obstructive urinary symptoms. FDG PET/CT and delayed pelvic PET/MRI showed significant circumferential thickening of the urethral wall with intense diffuse activity (SUVmax, 13) and multiple hypermetabolic lymph nodes in pelvic, retroperitoneal, mediastinal, pulmonary hilar, and axillary regions. This case indicates that IgG4-related urethral disease should be included in the differential diagnosis of FDG-avid urethral or periurethral lesions.